Mira

Overview

Trojan:Win32/Mira (also tracked across vendor signatures as Worm:Win32/Mira, distinct from the Linux IoT botnet Mirai) is a prolific Windows mass-mailing worm and backdoor downloader discovered in the late 2000s. Engineered to spread autonomously across corporate networks, Mira harvests email addresses from local address books, browser caches, and document folders, using its built-in SMTP engine to transmit spoofed emails carrying infected executable attachments. In addition to mass mailing, Mira scans for open network shares and connected removable USB storage devices to copy itself under deceptive filenames. Once active, Mira registers Windows Run keys to ensure persistence, collects host reconnaissance telemetry, and connects to remote C2 infrastructure to download second-stage malware payloads.

Known aliases

Threat reports may refer to this family under multiple names:

• Mira
• Trojan:Win32/Mira
• Worm:Win32/Mira
• W32/Mira
• Win32/Mira
• Trojan.Mira
• Worm.Mira

Threat Actor Attribution

Attribution is probabilistic, not a science. Each link below states its confidence level and the evidence behind it.

• Underground Cybercrime Groups High confidence
  Basis:

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Known Derivatives & Downstream Variants: Mira.A Mass-Mailer · Mira.B Network Spreader · Mira Downloader Build

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
• T1071.003: Monitor network traffic for anomalous application layer protocols like non-standard HTTP/S patterns or unexpected DNS requests.
• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
• T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2008-4250 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2010-2568 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

Command & Control (C2) and Network Profile

How this family talks to its operators. C2 traffic can often identify a family even when its code and configuration are hard to analyse. Ports and patterns are historical and change between campaigns, so use them as hunting leads rather than block-only rules.

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• 2c3d4e5f6a7b8091a2b3c4d5e6f708192a3b4c5d6e7f8091a2b3c4d5e6f70812
• 9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a01

Delivery vectors

• email_mass_mailing
• network_share_replication

Persistence mechanisms

• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
• Windows System32 binary drops

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_MIRA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Mira"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "mira" ascii wide nocase
        $s2 = "mira" ascii wide nocase
        $s3 = "trojan:win32/mira" ascii wide nocase
        $s4 = "worm:win32/mira" ascii wide nocase
        $s5 = "w32/mira" ascii wide nocase
        $s6 = "win32/mira" ascii wide nocase
        $s7 = "trojan.mira" ascii wide nocase
        $s8 = "worm.mira" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Mira (Worm) Execution & Triage
id: c2ffe337-7ac3-50af-8c4a-4da0319e3306
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Mira malware family. Detects suspicious execution from temporary user directories
  with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/mira
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.worm
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1071_003
- attack.t1091
- attack.t1105
- attack.t1059_003
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_MIRA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Mira tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "mira" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Block outbound SMTP connections (port 25) originating from employee workstations to stop email worm propagation.
2. Isolate compromised endpoints and scan internal file shares for dropped worm binaries.
3. Remove unauthorized registry entries from HKLM and HKCU Run keys created by the malware.
4. Apply security updates patching historical Windows Server and SMB flaws (MS08-067).

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not permit unrestricted direct outbound SMTP traffic from client desktop subnets.
2. Avoid opening executable email attachments received from unverified external contacts.
3. Never leave local network shares open with unauthenticated write permissions.

References & External Analysis

• Microsoft Security Intelligence: Trojan:Win32/Mira Assessment
• Symantec Security Response: Worm.Mira Threat Analysis
• NIST National Vulnerability Database CVE-2008-4250
• Search "mira" on VirusTotal (External Analysis)
• Search "mira" on Any.Run (Sandbox Sandbox)
• Search "mira" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Worm)

Explore other documented threats in the same operational category:

• Sfone
• Brontok
• Mogoogwi
• Lovgate
• Mofksys
• Chir
• Brambul
• Hworld

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/mira.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.